There are many terms which translate easily across all languages, having a universal meaning that can be thought of as loan-words or short-hands for other terms.
Many names of things cannot be remembered due to Physics: Detranslation phenomena. As such, they are given new names based on their remembered attributes, even if clear and specific memetic facts (such as events and identities) are unavailable. It is widely believed that speaking of the detranslated (particularly the empire) as incredibly bad luck - and as such is regarded as taboo: Typically only those who professionally deal with travellers who emerge from Elsewhere or Neverwhere are expected to know these terms.
Elsewhere is known to be an incredibly violent and young universe full of bloodshed, greed and corruption on a scale scarcely imaginable. Those who emerge from Elsewhere are generally not to be trusted until proven otherwise.